exercise4_3.java

Introduction to java programming 一书中所有编程练习部分的源码

// Exercise4_3.java: Create a method for computing future value
import javax.swing.JOptionPane;

public class Exercise4_3 {
  public static void main(String[] args) {
    // Enter yearly interest rate
    String annualIntrestRateString = JOptionPane.showInputDialog(
      null, "Enter yearly interest rate, for example 8.25:",
      "Exercise 4_3 Input", JOptionPane.QUESTION_MESSAGE);

    // Convert string to double
    double annualInterestRate = 
      Double.parseDouble(annualIntrestRateString);

    // Enter loan amount
    String loanString = JOptionPane.showInputDialog(null, 
      "Enter loan amount, for example 120000.95:",
      "Exercise 4_3 Input", JOptionPane.QUESTION_MESSAGE);

    // Convert string to double
    double loanAmount =  Double.parseDouble(loanString);
    
    System.out.println("Years\tFuture Value");

    for (int i = 1; i <= 30; i++) {
      double futureValue =
        futureInvestmentValue(loanAmount, annualInterestRate / 1200, i);
      System.out.println("" + i + "\t" + (int)(futureValue * 100) / 100.0);
    }
    
    System.exit(0);
  }

  public static double futureInvestmentValue(double investmentAmount,
    double monthlyInterestRate, int numOfYears) {
    return investmentAmount * Math.pow(1 + monthlyInterestRate,
      numOfYears * 12);
  }
}